With advantages such as small mechanical wear, low noise, low energy consumption and the like, a magnetic levitation bearing is widely used in ultra-high speed mechanical equipment.
FIG. 1 shows a structural schematic diagram of a magnetic levitation bearing assembly comprising a magnetic levitation bearing and a shell in the prior art. As shown in FIG. 1, in the prior art, the magnetic levitation bearing assembly comprises a magnetic levitation bearing and a shell 5′, wherein the magnetic levitation bearing comprises a first iron core 1′, a second iron core 2′, a thrust disc 3′, a rotating shaft 4′, a first coil 6′ and a second coil 7′, the thrust disc 3′ is fixed to the rotating shaft 4′, the first iron core 1′ and the second iron core 2′ are disposed at the two sides of the thrust disc 3′ along the axial direction of the thrust disc 3′, the first iron core 1′ is provided with a first coil accommodating portion for mounting the first coil 6′ and a first mounting portion for connecting the shell 5′, the second iron core 2′ is provided with a second coil accommodating portion for mounting the second coil 7′ and a second mounting portion for connecting the shell 5′, and in the axial direction of the thrust disc 3′, the first mounting portion and the second mounting portion are both fit to the shell 5′. The spacing between an end of the first mounting portion away from the thrust disc 3′ and another end of the second mounting portion away from the thrust disc 3′(an assembly size matched with the shell 5′) is L2′, the spacing between the first coil accommodating portion and the thrust disc 3′(a first working clearance) is X1′, the spacing between the second coil accommodating portion and the thrust disc 3′(a second working clearance) is X2′, and the axial length of the thrust disc 3′ is L0′, therefore, if a sum of the first working clearance X1′ and the second working clearance X2′ is defined as the working clearance of the magnetic levitation bearing, the working clearance of the magnetic levitation bearing is equal to X1′+X2′.
The bearing capacity of the magnetic levitation bearing mainly depends on the working clearance, and when the working clearance of the magnetic levitation bearing deviates, the bearing capacity of the magnetic levitation bearing cannot meet the load requirements, and it may even cause problems such as magnetic levitation failure and product becoming useless and the like. As can be seen, whether the actual working clearance and the preset value of the magnetic levitation bearing are consistent is a key indicator for evaluating whether the bearing capacity of the magnetic levitation bearing meets the design requirements. However, since the machining and assembly errors are difficult to avoid, the actual working clearance often deviates from the preset value of the magnetic levitation bearing. In this case, the working clearance of the magnetic levitation bearing needs to be adjusted.
Based on the existing magnetic levitation bearing assembly structure, the working clearance is mainly adjusted by turning or grinding the end of the iron core, which is specifically as follows:
(1) When the working clearance is greater than the preset value and the deviation thereof is ΔL, an end of the second mounting portion close to the thrust disc 3′(namely the left end of the second mounting portion corresponding to the assembly size L2′ in FIG. 1) is turned to the right by ΔL, so that a spacing ΔL is generated in the axial direction between the second mounting portion and the shell 5′, then the second iron core 2′ is moved to the left by ΔL to fit the second mounting portion with the shell 5′ again, so that the working clearance is reduced by ΔL, in this way, the working clearance is adjusted to conform to the preset value, and the purpose of adjusting the working clearance is achieved.
(2) When the working clearance is smaller than the preset value and the deviation thereof is ΔL, an end of the first coil accommodating portion close to the thrust disc 3′ (a right end of the first coil accommodating portion corresponding to the working clearance in FIG. 1) is turned to the left by ΔL, or an end of the second coil accommodating portion close to the thrust disc 3′ (a left end of the second coil accommodating portion corresponding to the working clearance in FIG. 1) is turned to the right by ΔL, then the working clearance is increased by ΔL, in this way, the working clearance is adjusted to conform to the preset value, and the purpose of adjusting the working clearance is achieved.
The above-mentioned method of turning or grinding the end of the iron core can adjust the working clearance, but it requires secondary processing of the iron core by turning or grinding, therefore, the processing cost is high, the adjustment difficulty is large, and the form and location tolerance of the secondary processing is difficult to guarantee, and it is liable to cause the working position of the iron core to be inaccurate. In addition, during the turning or grinding of the end of the iron core, the first coil 6′ and the second coil 7′ are prone to be damaged to affect the normal work of the magnetic levitation bearing, which results in electrical safety hazards, and may even directly cause the first coil 6′ or the second coil 7′ to become useless, increasing the production cost.